1. Field of the Invention
The present invention relates to a light source used for a projector for modulating light irradiated from a source lamp in accordance with image information to form an optical image and for enlarging and projecting the image, the light source including the source lamp, a reflector for aligning and emitting the light irradiated from the source lamp and a case for accommodating the source lamp and the reflector, and a projector provided with the source lamp.
2. Description of Related Art
Conventionally, a projector for modulating light irradiated from a source lamp in accordance with image information to form an optical image and for enlarging and projecting the image has been used.
Such projectors have been widely used for multimedia presentation in a meeting, scientific society, exhibition etc. Accordingly, in order to obtain vivid projected image by the projector, it is required for the light source to increase luminance thereof.
High-pressure mercury lamp or a metal halide lamp is used as the source lamp. When the life of the lamp expires, light-emitting tube thereof made of silica glass can be exploded to scatter the fragments around. Accordingly, the light source including the source lamp has a transparent glass plate etc. covering a light emitting surface of the reflector to prevent the fragments from scattering around even when the source lamp is exploded.
However, since the source lamp of the above-described light source is enclosed in a space defined by the reflector and the transparent glass plate, the temperature of the source lamp can become high so that the life of the source lamp can be shortened.
On the other hand, a cooling air-introducing opening may be formed on a part of the reflector and the transparent glass plate to cool the light-emitting tube. However, if an opening is formed, it is difficult to completely block the fragments from falling out when the source lamp is exploded.
An object of the present invention is to provide a light source and a projector capable of preventing fragments from falling out to the outside even when the source lamp is exploded and capable of efficiently cooling the source lamp to lengthen the life thereof.
In order to achieve the above object, a light source according to an aspect of the present invention is used for a projector for modulating a light irradiated from a source lamp to form an optical image in accordance with image information and enlarging and projecting the optical image, the light source including: a source lamp; a reflector for aligning and emitting the light irradiated from the source lamp; and a case for accommodating the source lamp and the reflector, where a light-emitting surface of the reflector is covered by a light-transmissive plate and a pair of openings is formed on a contact surface of the light-transmissive plate and the reflector, the pair of openings being symmetrically disposed around an optical axis of the reflector, and where the case includes a cooling channel for introducing a cooling air to the source lamp through the pair of openings and a cooling channel shutter for shutting the cooling channel when the case is detached from the projector and for opening the cooling channel when the case is attached to the projector.
The above-described pair of openings may be formed by cutting a part of the light-transmissive plate, however, preferably be a recess formed by cutting a part of a distal end of the reflector in the light-emitting direction. This is because the cooling air can be flowed in a direction orthogonal with the optical axis of the reflector and around the source lamp as a heat source, so that the source lamp can be efficiently cooled. In this arrangement, the pair of openings may preferably be disposed in horizontal direction when the case is detached from the projector.
The case for accommodating the source lamp and the reflector refers to a case having a positioning surface for positioning the source lamp and the reflector in an optical axis direction of the irradiated light beam and in a direction orthogonal with the optical axis, which may be arranged as a molding made of plastic by injection molding etc.
According to the above aspect of the present invention, since the cooling channel for introducing the cooling air to the source lamp through the pair of openings is formed on the case, the source lamp can be efficiently cooled to lengthen the life of the source lamp.
Further, since the cooling channel shutter for shutting the cooling channel when being detached is provided, even when the light-emitting tube of the source lamp is exploded while using the projector, the fragments of the light-emitting tube do not fall outside in exchanging the light source. And since the cooling channel shutter opens the cooling channel when the case is attached to the projector, cooling efficiency of the source lamp is not impaired. When the light source is attached so that the pair of openings is horizontally disposed in detaching the case from the projector, the fragments of the light-emitting tube can be further securely prevented from falling outside in exchanging the light source.
In the above arrangement, the cooling channel shutter may preferably include a lid member rotatably supported to the case for shutting the opening formed on the case and a biasing member for biasing the lid member in rotary direction, or alternatively, may preferably include a lid member slidably supported by the case for shutting an opening formed on the case and a biasing member for biasing the lid member in slide direction thereof, which may be provided on one of, or both of air-introducing opening and air-exhausting opening of the cooling channel formed in the case.
Since the cooling channel shutter is made of a lid member and a biasing member, the cooling channel shutter can be provided on the case with a simple arrangement, so that the light source can be easily produced.
In the above, the case may preferably be provided with a duct for guiding an air from an outside of the case to the cooling channel and/or from the cooling channel to the outside of the case.
By forming the duct to the case, introduction of cooling air from outside the case and discharge of the after-cooling air to the outside of the case can be conducted at a position corresponding to the cooling channel in the projector, so that cooling efficiency of the light source can be further enhanced.
Further, a dust filter may preferably be provided on the pair of openings.
The dust filter may only be provided to the air-introducing opening or to the air-exhausting opening, or alternatively to both of the pair of openings.
Since the dust filter is provided, the fragments can be securely prevented from falling out of the case even when the light-emitting tube of the source lamp is exploded. Further, when the dust filter is provided to the air-introducing opening, the dust invasion in accordance with introduction of the cooling air can be prevented, thus avoiding decrease in luminance when the light-emitting tube gets dirty.
A projector according to the present invention includes the above-described light source, which can obtain the same function and effects as in the above.
In the above projector, a duct having an end inserted to the cooling channel shutter while being attached to the light source for introducing the cooling air into the light source may preferably be provided.
By having such duct, the cooling air in the projector can be securely introduced into the light source, thereby further enhancing cooling efficiency of the light source and lengthening the life of the light source.
The duct may preferably include a fan on the base end thereof for transferring the cooling air, or when an exhaust duct for discharging the air having cooled the inside of the light source is provided, the base end of the duct may preferably be connected to the exhaust duct.
Since the fan is provided to the duct or the duct is connected to the exhaust duct, the cooling air can be forcibly transferred from the duct to the cooling channel, so that the circulation of the cooling air can be enhanced to improve the cooing efficiency of the light source.